Aerial refueling allows for increased effective range and extended operation of aircraft, traditionally in military and transport operations and potentially in future commercial freight and passenger aircraft. Aerial refueling involves a supply aircraft, or “tanker,” that carries a fuel supply and provides an aerial refueling system that can engage a receiving aircraft to transfer fuel from the fuel supply to the receiving aircraft while both aircraft are in-flight. One commonly used aerial refueling system is the “boom and receiver” system, in which a boom coupled to a rear portion of the tanker is deployed to engage the receiving aircraft. The boom normally includes a rigid, aerodynamically shaped portion coupled with a telescoping extension positioned at an end of the boom. The telescoping extension includes a nozzle configured to be received by a fuel receptacle of the receiving aircraft.
The aerodynamic portion of the boom further includes a ruddevator assembly, generally comprised of airfoils, that permits a refueling operator in the tanker to maneuver the boom and nozzle relative to the receiving aircraft. During an aerial refueling operation, the operator may release the boom from a stowed position and extend the telescoping portion of the boom. The boom may then be directed towards the receiving aircraft by controlling the aerodynamic surfaces to guide the end of the boom containing the nozzle into the fuel receptacle on the receiving aircraft. While the nozzle and fuel receptacle are coupled, the telescoping extension may permit fuel to be continuously transferred by accommodating small relative motions occurring between the tanker and the receiving aircraft.
A goal of the aerial refueling system is to deliver fuel at the nozzle at a specific flow rate and a specific pressure. Controlling the delivery fuel pressure to the highest specified delivery pressure may minimize receiver time on the tanker boom of the receiving aircraft and avail the tanker for other aircraft needing to be refueled. While the flow rate may vary based on the type of the receiving aircraft being refueled, the pressure at the interface between the nozzle and the fuel receptacle should remain within defined tolerances for efficient refueling operations. If the pressure of the fuel at the nozzle is too low, the refueling may not take place or may not be efficient. If the pressure is too high, the refueling operation may cause damage to the fuel systems and/or plumbing of the receiving aircraft.
In traditional boom/receiver-type aerial refueling systems, the pressure of the fuel at the nozzle is traditionally controlled by a pressure regulator in the fuel supply system located inside the fuselage of the tanker that regulates the pressure and flow of fuel at a point before it enters the boom. However, pressure drops or gains may occur within the boom as the fuel flows downstream to the nozzle due to factors such as the elevation azimuth of the boom, the extension length of the telescoping portion, the flow rate of fuel through the boom, the temperature of the air outside the boom, and the like. Further, changes to the position, elevation azimuth, and extension length of the boom during the refueling operation may cause the pressure at the nozzle to vary throughout the operation, affecting refueling efficiency as well presenting safety issues.
It is with respect to these and other considerations that the disclosure made herein is presented.